The pair separated in May (13) after 18 months together, but they have now decided to give the romance a second shot.

A source tells Usmagazine.com, "They are back seeing each other, they do have a great time. They are trying to be fairly quiet about it, but they're not staying in a bunker or anything. Just a little more discrete."

Lutz proved there was no bad blood between him and his Australian ex-girlfriend in July (13) when he reached out to wish her a happy birthday.

In a post on Twitter.com, he wrote, "Huge Happy Birthday to the amazing Sharni Vinson (Sydney Time) and a Happy Birthday to the wonderful (her mother) Narelle Vinson for bringing such a beautiful soul into this world!"